1. EXPERIMENTAL DESIGN
Science answers questions with experiments

2. Begin by asking a question about an observation or problem
Start by: DEFINING THE PROBLEM
Begin by asking a question about an observation or problem
What is a good question for an experiment?
One that is testable with the materials at hand

3. Chances are, something is already known about your observation/problem
Perform background research
Chances are, something is already known about your observation/problem
Why is it important to do background research?
Your question may already have an answer!

4. Form a hypothesis
What is a hypothesis?
An if...then… statement to explain what is causing the observation/problem.

5. Design an Experiment Designed experiment must test hypothesis
This experiment will allow you to change some conditions or variables to test your hypothesis.

6. Variables Variables are things that change.
The independent variable is the variable that is purposely changed. The variable set-up by experimenter
The dependent variable is influenced by the independent variable. The variable measured by the experimenter.

7. Constants or Controlled Variables in an Experiment
What are constants in an experiment?
Factors that are kept the same and not allowed to change.

8. Materials and Procedures
A description of what you will use for your experiment, and how you will do it.

9. Repeated Trials What are repeated trials?
The number of times that the independent variable is tested.
Why are repeated trials necessary?
They reduce the possibility of chance errors affecting the results.

10. How does the length of the blade (spiny thing) impact its flight?
Example experiment
I like HELICOPTERS.
How does the length of the blade (spiny thing) impact its flight?

11. Writing problem statement
How do you phrase it?
“The Effect of the Independent Variable on the Dependent Variable”.
The effect of wing length (Independent V.) on time of descent (Dependent V.)

12. Variables have units! Length of one wing as measured in centimeters
Independent variable:
Length of one wing as measured in centimeters
Dependent variable:
Time of descent as measured in seconds

13. Title for the Helicopter Experiment
The Effect of Wing Length on the Length of Time the Helicopter Takes to Reach the Ground

14. Another Look at Our Hypothesis
INDEPENDENT VARIABLE
If the length of the wings are increased,
DEPENDENT VARIABLE
then time of descent will increase.

15. Constants in an Experiment
Factors that are kept the same and not allowed to change
What should be kept constant in the“Helicopter”?
CONSTANTS
Same structure of helicopters
Same dropping technique
Same dropping height

16. Values of the Independent Variable
How many different values of the independent variable should we test?
Enough to clearly illustrate a trend in the data - 5cm, 6cm, 7cm, 8cm…..

17. How many repeated trials are needed in the “Helicopter”?
At least 3, then calculate an average value for each level of the independent variable